1. Field of Invention
The present invention relates to an open-end ratchet wrench, and more particularly to an open-end ratchet wrench adapted for reducing tooth gaps between a ratchet wheel and a ratchet pawl thereof, and prolonging a lifespan of the wrench.
2. Description of Related Arts
A conventional ratchet wrench is not suitable for operation on a cool air pipe nor an oil-pressure pipe, so that an open-end wrench has to be used instead. Therefore, a conventional open-end ratchet wrench has been developed in view of this inconvenience. But the current open-end ratchet wrench has several disadvantages as follows.
Firstly, when a coupling tooth portion of a ratchet pawl is coupled with an outer tooth portion of a ratchet wheel, tooth gaps are inevitably formed between the coupling tooth portion and the outer tooth portion. Thus, unwanted noise and vibration are produced during operation, and positioning errors and unsatisfied performance are also easy taken place.
Secondly, an opening of the ratchet wheel is not provided at a position along a center line of the wrench handle, so that two ratchet pawls cannot be symmetrically provided at two sides of the center line. Therefore, when a user applies a single direction force to drive the wrench handle, stress is easy to be concentrated on the ratchet pawls and the coupling tooth portion of the ratchet pawls may prone to break up, so that the life span of the wrench is not relatively long.
Thirdly, this kind of open-end ratchet wrench is neither motor driven nor air driven. Accordingly, a user has to manually operate on the wrench handle, so that this kind of wrench is hard to meet a requirement of effective and efficient operation performance.